Locking-bolt actuating means for machine guns



` Dec. 21, 1943. T. R. ROBINSON, JR

LQCKING BOLT ACTUATING MEANS FOR MACHINE GUNS Filed March 9, 1945 2 Sheets-Sheet 1 m. ,I Lw N@ wmm mm x www: O @New ooloo ooooo O @n Mt bm nu www s,-.- l @LLLII om mm VI* O a o o 1, o oo @F m. Q

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. Fl'ed March 9, 1943 2 Sheets-Sheet 2 Dec. .'21, 1943. T .R. ROBINSON, JR f A2,337,273

LOCKING BOLT AQTUATING MEANS FOR MACHINE GUNS Patented Dec. 21, 1943 LOCKING-BOLT ACTUATING MEANS FOR `MACHINE GUNS Thomas R..Robinson,f.r., New Haven, Conn., alssignor to The High Standard Manufacturing Company, Incorporated, Hamden, Conn., a corporation of Connecticut Application Marchi), 1943, Serial No. 478,489

2 Claims.

vThe present invention relates to improvements in machine guns and relates more particularly to the actuating-means for effecting the retirement of the locking-bolt which serves to lock the breech-bolt in its rbreech-closing position to thereby permit the retirement of the said breechbolt .away from its breech-closing position.

In machine guns the rapidity of operation of the mechanism (very often more thanone thousand cycles per minute) imposes great stresses on the actuating-means which serves to retire the locking-bolt to thereby permit the movement voi the breech-bolt out of its breech-closing position, and one of the objects of the present invention .is to provide a superior actuating-means which will withstand such strains over long periods of `use and under conditions where speedsareapproaching the maximum.

Another object of the present invention is -to provide a machine gun with superior locking-bolt actuating-means which will withstand the severe strains imposed upon it but which Aat the same time .may be assembled with rapidity and `economy and without requiring excessively-skilled Workmen.

A further object of the present invention :is to provide a machine gun with superior lockingbolt actuating-means which is mounted for slight pivotal movement and in which the pivot-means is so constructed and arranged as to effectively resist the shocks imposed upon the locking-'bolt actuating-means by the rapid and long-continued operation of the machine gun.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel vover the prior art and which are not claimed in any separate application.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrativeA purposes:

Fig. 1 is a View in side elevation of a. machine gunequipped with the present invention;

Fig. 2 is a broken view partly in side elevation and partly in vertical central-longitudinal section of the rear-portion .of the machine gun shown in Fig. r1 with the parts shownin the positions which they assume when the breech-bolt is in its normal breech-closing position;

Fig. 3 is a view corresponding to Fig. 2 but showing the parts in the positions which they assume when the barrel and barrel-extension `have recoiled to substantially the limit of their rearward travel and the breech-bolt has been unlocked and moved rearwardly with respect to the barrel-extension;

Fig. 4 is a broken transverse sectional view taken on the line 4 4 of Fig.2;

Fig. 5 is a broken View Aof the forward-portion of the buffer-housing together 'with the lockingbolt `depressors therein;

'-Fig. 6 is a view mainly in top or plan .elevation and partly in section taken on the line 5..-6 of Fig. 5;

Fig. 7 is a transverse .sectional view `taken on the line l-l of Fig.-5;

Fig.,8 is a lbroken perspective view oi the forward-portion 4of the buier-housing, detached;

Fig. 9 is a similar view of .one of the lockingbolt depressors, detached; and

Fig. 10 `is a perspective view of one-.of the pivotstuds, detached.

The particular machine gun herein chosen for purposes of illustrating one form .of the vpresent invention is of the so-called Browning type and is of lthe general type illustrated in .detail .in United States Patent No. 1,628,226, dated May 10, 1927.

As before noted the present invention relates to the means whereby the :locking-bolt which locks the vbreech-bolt in its breech-closing position, is actuated for releasing such Ybreech-bolt, and therefore only the :said .features plus related features Vwill be described herein.

The machine gun illustrated in the Vaccompanying drawings vincludes a lreceiver .generally designated by the reference character I5, an axially-reciprocating lbarrel 4.6, a Vbarrel-extension I1, 1a Ibreech-bolt I8 and a perforated barreljacket I9.

The A.barrel I6 has its rear `portion extended within the receiver I5 for `reciprocation therein andthe aforesaid .barrel-extension .I l is organized with the rear end of kthe .barrel for reciprocation also within the receiver I5, in a manner well known in the art. The breech-'bolt vI8 is guided for longitudinal reciprocation relative to theibarrel-extension I I by beingtted into alongitudinal upwardly-opening guide-channel 2G formed in the upper face of the barrel-extension Ill, andis normally yieldingly urged forwardly .into its breechclosing position by 4a .helical breech-closing spring 2tI.

In its under face adjacent its rear end, .the breech-bolt I8 is formed with a transverselyextending Yand downwardly-opening lockinggroove 22 having a ;rearwardly-and-upwardlysloping ,transverse .locking-abutment .2.3 which faces generally rearwardly and downwardly.

The barrel-extension I1 is formed at its rear with a depending-lug 24 which is formed with a vertical guideway 25 having its upper end intersecting the longitudinal guide-channel in which the breech-bolt I8 reciprocates. At its lower end the vertical guideway intersects a longitudinal downwardly-opening groove 23 formed in the under face of the lug 24 of the barrel-extension I1, as is indicated in Figs. 2, 3 and 4.

Mounted for vertical reciprocal-,ion in the vertical guideway 25 in the barrel-extension I1, is a locking-bolt 21 which has its forward upper corner upwardly and rearwardly sloped to provide a cani-like locking-abutment 28 facing in a direction which is generally forwardly and upwardly and corresponding in slope to the locking-abutment 23 of the breech-bolt I8.

Projecting outwardly from each of the respective opposite sides of the locking-bolt 21 is one of two actuating-pins 25-23, each of whichV extends outwardly through one of two similar vertical clearance-slots S--S formed respectively in the adjacent side walls of the lug 24 of the barrel-extension I1. Each of the clearanceslots 30-30 intersects the adjacent one of two longitudinal clearance-recesses 3I-3I respectively formed in the opposite 4side faces of the depending-lug 24 of the barrel-extension I1 and each intersecting the rear face of the said lug.

Rigidly secured to the upper face of the bottom wall of the receiver l5 is a block 32 extending longitudinally in the downwardly-opening longitudinal groove 26 in the bottom face of the lug 24 of the barrel-extension I1. The forward portion of the block 32 is formed with an upwardly-projecting lifting-lug 33 having a rear- Wardly and downwardly -inclined rear face adapted for cam-like engagement with the forward lower corner of the locking-bolt 21 before referred to.

Located in the lower rear portion of the interior of the receiver I5 at a point to the rear of the depending-lug 24 of the barrel-extension I1 vis a bar-like housing 34 suitably anchored in place within the said receiver.

As is shown particularly well in Figs. 5, 6 and 8, the housing 34 includes two side-walls 35-35 both projecting forwardly beyond the top-wall 36 thereof. Each of the said side-walls 35--35 is formed in its outer face with a longitudinal groove-like recess 31 intersecting the forward edge of the particular side-wall in which it is formed, land at its rear end communicating with a transverse cylindrically-contoured passage or socket 38. In both its upper and lower walls, each of the recesses 31 before referred to is formed with a central-longitudinal retaininggroove 39. The retaining-groove in the upper wall of each of the recesses 31 is downwardlyopening and intersects the forward end of the side-wall in which it is formed, while the retaining-groove 39 in the complemental lower wall of each of the recesses 31 opens upwardly and, in turn, intersects the forward end of the said side-wall.

. The transverse cylindrically-contoured passage 38 in each of the side-walls 35 of the housing 34 extends completely through such sidewall and has a diameter substantially corresponding to the vertical distance between the respective bottoms of the complemental retaining-grooves 39-39 in a given side-wall 35.

Mounted in each of the two longitudinal recesses 31 is one of two complemental bolt-depressing arms 45 which also extends into the outer portion of the advacent transverse passage 38 and has a cylindrically-contoured rear end 4I conforming thereto.

The rear portion of each of the bolt-depressing arms 4B is formed with two central-longitudinal retaining ribs 42-42 respectively formed on its upper and lower edges and sized to have a sliding fit within the pair of complementa] retaininggrooves 35i-39 in one of the two recesses 31 respectively formed in the side-walls 35-35 of the housing 34. The vertical distance between the outer surfaces of a given pair of comple- `mental retaining-ribs 42-42 is materially less than the vertical distance between the bottoms of the complemental pair of retaining-grooves 3.9-39 in the particular recess 31 in which the bolt-depressing arm iits, so that the forward ends of Vthe said arms may have vertical swinging movement for purposes as will hereinafter appear and as indicated by broken lines in Fig. 5. At its extremeA rear end the inner face of each of the bolt-depressing arms 40 is formed with a notch 42a arranged concentric with a transverse bore 43 and flush with the plane of the two complemental retaining-ribs 42-42, as is especially well shown in Fig. 9. Seated in the notch 42a of each of the respective bolt-depressing arms 40 isthe cylindrically-contoured head 44 of a retaining-l stud generally designated by the reference character 45 and including also an integral relativelyslender shank 46 projecting concentrically from one face of the said head 44. The shank 46 projects outwardly through the bore 43 in the arm 40 of which it forms a part'and is swaged over as at, 41 to rigidly unite the stud with theappropriate arm.

The head 44 of a given retaining-stud 45 has a diameter appropriate for a smooth turning fit in the cylindrically-contoured passage or socket 33 in which it fits and has a thickness in an axialdirection sufficient to project inwardly from the notch 42a of its arm 40 a distance sufficient to have its inner face flush with the inner face of the side-wall 35 in which it is mounted and as is especially well shown in Fig. 6. By bearing against the relatively-thin cylindrically-contoured forward portion of the transverse passage 38, the head 44 serves to retain the bolt-depressing arm 40 of which it forms a part against forward lengthwise displacement, while permitting the desired vertical swinging movement of the said arm, as indicated by broken lines in Fig. 5. Furthermore, the rear portion of the periphery of the. head 44 bears against the rear portion of the vpassage 38 and, in conjunction with the cylindrically-contoured rear end 4I of the arm 40 of which it forms a part, serves to absorb violent shocks and prevent the rearward displacement of the said bolt-depressing arm.

In assembling a given bolt-depressing arm 40 with the housing 34, the rear end of the arm in question is inserted rearwardlyk (with the notch 42a facing inwardly) into the chosen recess 31v so that the retaining-ribs 42-42 of the arm t into the complemental retaining-grooves 35i- 39.A The rearward movement of the arm is continued until its cylindrically-contoured rear end 4I abuts against the rear wall of the transverse passage 38 in the chosen side-wall 35. The retainingstud 45 is now installed through the inner end of the transverse passage 38 so that its head 44 seats in the notch 42a of the arm 40 and the 'shank 45 of the retaining-stud extends through the bore 43 in the bolt-depressing arm. 'The outer end of the shank 46 'is now headed over into the slightly rcountersunk outer end of the bore 43 in the arm 40 so that the stud 45 becomes a rigid unitary part of the said arm.

As thus assembled, the given bolt-depressing arm 4B is free to swing to a small degree about the axis of the retaining-stud 45 as a pivot and is retained against forward longitudinal displacement by the engagement of the periphery of the relatively-large head 44 with the relatively-thin forward wall of the transverse passage 38. By virtue of the longitudinal retaining-ribs 42--42 fitting within the retaining-grooves 39-39, the lateral displacement of the given bolt-depressing arm is prevented while permitting the pivotal movement above referred to.

Upon the discharge of the machine gun and in a manner well understood in the art, the barrel I6, barrel-extension l1 and breech-bolt I8 will move rearwardly relative to the receiver I5, housing 34 and the remaining relatively-stationary parts of the machine gun. This movement will carry with it the locking-bolt 21 which will remain in its upper or breech-bolt-locking position until its forward lower corner reaches registration with the downwardly-and-rearwardly-sloping rear face of the lifting-lug 33 which is rigid within the central lower portion of the receiver l5, as before explained. At about the time that the locking-bolt 2 reaches a position where its forward lower corner is in registration with the sloping face of the lifting-lug 33, the actuating-pins 29-29 of the locking-bolt will engage with the rearwardly-and-downwardly-inclined cam-surface i8 of the respective boltdepressing arms dil-d. If by the time the actuating-pins 29-29 engage with the respective cani-surfaces 1S-d8, the locking-bolt 2 has not been moved downwardly, then the engagement just referred to will eiect the downward movement of the said locking-bolt in a positive manner.

In absorbing the shock of the engagement of the actuating-pins ZS-Z, the forward portions of the respective bolt-depressing arms l0- 4D will be supported against undue upward displacement by the ccmplemental upper wall of the adjacent clearance-recess 3i in the lug 2d of the barrel-extension il'. The shock of the actuatingpins f2s-253 engaging the respective bolt-depressing arms l-llll will also be transmitted lengthwise of the said arms to the rear portions of their respective passages 38-38 which also serve, as previously pointed out, to prevent the bolt-depressing arms Lic-fle from being rearwardly displaced.

When during their rearward movement the barrel i and barrel-extension Il reach the positions in which they are shown in Fig. 3, the locking-bolt 2l will be fully depressed, thereby freeing the breech-bolt i8 for continued rearward movement into substantially the position in which it is shown in Fig. 3, while the said barrel and barrel-extension are checked, after but a relatively-slight rearward movement, in substantially the position in which they are shown in the said Fig. 3.

By means of the present invention, though relatively slight in physical aspects, machine guns are enabled to perform satisfactorily and at high rates of speed, since the shocks imposed upon the bolt-depressing or bolt-actuating arms 4G are so well distributed in the housing 3d or its equivalent that the loosening of the said arms to any material extent is guarded against and therefore the performance of the machine gun is made consistent and reliable.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential charac-- teristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to.be embraced therein.

I claim:

1. Amachine gun including in combination: a receiver; an axially-movable barrel; a barrelextension united with the rear of the said barrel and reciprocating in the said receiver; a breechbolt associated with the said barrel-extension and movable therewith and also movable longitudinally with respect thereto in a direction lengthwise of the machine-gun structure; a locking-bolt carried by the said barrel-extension and movable vertically with respect thereto to lock and unlock the said breech-bolt to and from the said barrel-extension; a vertical wall-portion located in the said receiver t-o the rear of the said barrel-extension and having a longitudinal recess therein opening through one side of the said wall-portion and also intersecting the forward end thereof, the said wall-portion also having a transverse passage extending therethrough in intersecting relationship with the rear of the said longitudinal recess; a bolt-actuating arm having a rear-portion fitting within the recess in the said wall-portion and having a forward-portion projecting forwardly into position to engage with a portion of the said locking-bolt to actuate the latter, the rear-portion of the said bolt-actuating arm being formed with a transverse bore registering with the transverse passage in the said wall-portion and having a diameter materially less than the diameter of the said transverse passage; a retaining-stud comprising a relativelylarge-diametered head having a rotating t in the transverse recess in the said wall-portion, the said retaining-stud also having a relativelysmall-diametered shank secured in the transveres bore in the rear portion of the said boltactuating arm, the head-portion of the said retaining-stud being tightly held by the said shank against the side face of the arm which faces toward the recess in the said wall-portion; and retaining-means independent of the said retaining-stud and holding the said actuating-arm in the recess in the said wall-portion against lateral displacement therefrom.

2. A machine gun including in combination: a receiver; an axially-movable barrel; a barrelvextension united with the rear of the said barrel and reciprocating in the said receiver; a breechbolt associated with the said barrel-extension and movable therewith and also movable longitudinally with respect thereto in a direction lengthwise of the machine-gun structure; a locking-bolt carried by the said barrel-extension and movable vertically with respect thereto to lock and unlock the said breech-bolt to and from the said barrel-extension; a vertical wall-portion located in the said receiver to the rear of the said barrel-extension and having a longitudinal having a rear-portion fitting Within the recess in the said Wall-portion and having a forwardportion projecting forwardly into position to engage with a portion of the said locking-bolt to actuate the latter, the rear-portion of the said bolt-actuating arm being formed With a transverse bore registering With the transverse passage in the said wall-portion and having a diameter materially less than the diameter of the said transverse passage; a retaining-stud comprising a relatively-large-diametered head having a rotating fit in the transverse recess in the said Wallportion, the said retaining-stud also having a relatively-small-diameter-ed shank secured in the transverse bore in the rear portion of the said bolt-actuating arm, the head-portion of the said retaining-stud being tightly held by the said shank against the side face of the arm which faces toward the recess in the said Wall-portion; and longitudinally-extending intertting-riband-groove retaining-means independent of the said retaining-stud and holding the said actuating-arm in the recess in the said Wall-portion against lateral displacement therefrom. l

THOMAS R. ROBINSON, JR. 

